Noise control is becoming a necessity in noise polluting environments, such as in buildings of industrial, commercial, educational or recreational activities. Such usages often demand not only sound insulation of the walls surrounding the buildings, but noise controlling means close to the source of noise pollution within the building. If this is the case, the requirement arises for a supporting structure being filled with sound absorbing panels close to the source of noise pollution and surrounding the same, aiming at delimiting the source of noise pollution by providing a sound insulating barrier that may inhibit dissemination of noise in the surrounding environment.
The panels being employed in such sound insulating barrier structures are conventionally of large dimensions, typically 2.00×0.60 m rectangular panels bearing a sheet metal plate covering on either surface of the sound insulating material being encaged in between, wherein the sheet metal plate covering facing towards the noise polluting source is perforated so as to ensure noise absorption as sound waves fall upon the openings provided in the perforated sheet metal plate covering. Such panels are provided with alternatively matching side projecting protrusions and protrusion receiving recessions along their lengthier sides, so as to form a sound insulating panel assembly of adjacently matching panels that form an integral wall structure without any intermediate gaps and/or joints. The shorter sides of such rectangular panels are covered by a Π shaped sheet metal laminate offering protection of the encaged sound absorbing material, thereby resulting in an H shaped sheet metal laminate configuration of adjacent panels.
Anchorage of the aforementioned panels onto the ground requires special reinforcing structures such as heavy duty anchoring means or chemical additives, whilst building of a wall structure with the abovementioned panels and supporting structure of the same necessitates the employment of hoist equipment to lift each sound insulating panel at the top of the supporting structure and henceforth letting it slide along the supporting structure so as to effect a matching contact with neighboring panels by means of engagement of the abovementioned alternative panel protrusions and recessions.
A process of building sound absorbing walls with panels being fitted onto a supporting structure is disclosed in U.S. Pat. No. 3,934,382 (Gartung). In U.S. Pat. No. 3,748,799 (Tough et al) the sound absorbing panels are provided with a perimetrical sheet metal laminate of Π configuration and are sequentially glued one onto the other by means of double-faced adhesive tapes. In U.S. Pat. No. 4,194,329 (Wendt) the sound absorbing panels are provided with a circumferential Π sheet metal laminate and form units by encaging an assembly of panels with a Π shaped sheet metal frame extending about the outer edge of the encaged panels, thereby forming heavy structures of large dimensions, whilst in U.S. Pat. No. 4,016,689 (Wendt) the circumferential Π sheet metal laminates in juxtaposed sound absorbing panels are joined by means of special metallic clips.
The hereinabove described sound insulating wall structures of the prior art are subject to the deficiencies of heavy on site labour employing cranes and tooling for building, connecting and anchoring the supporting structures without allowing for an independently carried out testing and certification process of the supporting structures, thereby resulting in the sound insulating wall becoming practically difficult or impossible to any change whatsoever following its building. However such a capacity to change might be required due to variation in the operation parameters of the noise polluting source in the course of time and/or to the requirement of replacement of damaged portions of the sound absorbing panels.
Furthermore if such a method of building the sound insulating wall structure is adopted, it will not allow, if the need arises, e.g. because of a relocation or expansion or differentiation of the production process in an industrial plant, safe transport of the structured sound insulating wall, since dismantling of the panels will damage many of them, whilst if sound insulation parameters vary in the novel working location, employment of the old panels might be not applicable therein. It is furthermore evident that the method of building sound insulating wall structures of the prior art results in either difficulties in ensuring access to areas of production machinery necessitating maintenance in industrial sites or in building the sound insulating surrounding walls at dimensions much larger than necessary, thereby increasing sound insulation cost and coverage of viable space by this production machinery. The cost of sound insulation structures with the abovementioned methods of the prior art is by all means elevated if one further takes into account the need of employing cranes and special tools, the special construction of the supporting structure in the same time as the assembly of the sound absorbing panels, the subsequent requirement of the simultaneous presence on site of all materials, both of those associated with building of the supporting structure and of the sound absorbing panels, as well as the compulsory employment of skilled personnel, but also of a greater number of workforce so as to adequately implement the structure and/or transport on site the bulky and heavy sound absorbing panels if the existent transporting infrastructure of elevators and/or staircases in a particular building does not offer handy transport or cannot accommodate transport of such items.
It is a principal object of the present invention to advantageously overcome the abovementioned drawbacks and deficiencies of the prior art by disclosing a sound absorbing panel that ensures an autonomy in the building of sound insulating wall structures as it may be added or removed from an already built sound insulating wall structure without any requisite preparatory process. Such independency of the sound absorbing panel of the invention from the supporting structure thereof leads to the beneficial outcome of a handy, rapid dismantling and reinstallation thereof, if a need arises due to damage or change in the operation parameters of the production equipment or relocation thereof or other, such dismantling and reinstallation process being carried out even by unskilled personnel and without employing cranes or special tools.
Another object of the present invention is to provide the proposed sound absorbing panel ready to use, industrially assembled, at dimensions substantially smaller than conventional dimensions of the prior art that will ensure handy transport thereof to mount onto a previously and independently constructed, tested and certified supporting structure, thereby ensuring in this way, in addition to the main advantage of autonomous building and addition/removal capacity, a substantial decrease in the installation cost as requirements of the prior art for machinery and tools are eliminated and requirements in the labour staff and most importantly of skilled labour are diminished.
Furthermore, the herein proposed sound absorbing panel provides for a rapid and safe dismantling thereof at any time and of re-installation at a new working location, wherein compatibility of prior and novel working locations is enhanced due to the smaller dimensions of the proposed sound absorbing panels. Finally, the herein disclosed sound absorbing panels ensure under all circumstances the cheapest solution in building sound insulating walls surrounding a specific production plant, whilst as mentioned hereinabove sound absorbing panels of the prior art are disadvantageously bulky and costly so as to ensure the necessary access to the production plant surrounded by a sound insulating wall structure.
Another problem manifested in relation to sound absorbing panels of the prior art is that with a scope of ensuring optimum sound absorption and rigidity of the panel structure, each panel, as mentioned hereinabove, is provided with a perforated metal plate covering at the side facing the noise polluting source. Such perforated metal plate covering however gives rise to reflection of a large percentage of the sound waves falling thereupon and thereby leads to difficulties in the elaboration of technical specifications for the sound insulating structure that by way of example has a rectangular configuration whereby a plurality of reflections take place that give rise to secondary noise emission sources. Furthermore, the method of building sound absorbing wall structures of the prior art results in an undesirably large vibrating surface that is as high as the overall structure and its width corresponds to the width of each one of the serially assembled panels, i.e. typically of the order of 2 m, with each panel fitted into its neighboring panels with the abovementioned alternatively formed side protrusions and corresponding recessions. Thus in the hereinabove method of building a sound absorbing wall structure of the prior art, the extensive vibrating sound absorbing structure is merely fixedly mounted onto the side pillars of the abovementioned Π shaped sheet metal edge coverings.
It is therefore an object of the present invention to advantageously overcome the hereinabove mentioned shortcomings of the prior art by providing the presently disclosed sound absorbing panel that ensures the necessary rigidity due to its substantially smaller dimensions, whilst with a scope of ensuring enhanced sound absorption properties and eliminating the reflective properties of the perforated sheet metal plate covering of the prior art and thereby rendering a reliable elaboration of technical specifications for the sound insulating structure for each particular application due to standardized sound absorbing characteristics of each one of the sound absorbing panels, each panel is provided with a sound absorbing covering of a flexible special sound absorbing type of plastic covering instead of the previously employed perforated sheet metal plate covering. Furthermore, a clearly enhanced rigidity of the panels of the invention as compared to sound absorbing panels of the prior art results due to the autonomy in the mounting of each one the herein disclosed sound absorbing panels onto the supporting structure thereof, whereby the resultant overall vibrating surface and rigidity thereof is determined by the dimensions of each one of the sound absorbing panels in themselves and is not related to the supporting structure and/or to the overall sound insulating wall structure.